Topic: Boosted Applications... Turbo/Supercharger

[HavocTurbo]

There was a time on here, where even talking about running a Magneto, would have a few posters jumping all over you, telling how bad it was!

Sorry man.... oh how times have changed!!  But since this is the HiPo forum and I have numerous photos of the man himself using his own drives, anyone who says it's bad can kiss me. 

Might even free up a lot of power from the stator... anyone got a idea how much exactly?

Uh oh, what's you're thoughts on full boost RPM?   Based on a totally different motor I'm seeing a T3 60ish A/R on the comp, small on the turbine spooling at 5-6k, think that's in the ball park? Much more top end play than quick on its feet off a green light.  But nothing too sluggish to get out of the hole with 9:1 stock compression.  I hope its not too stupid high of an RPM before full boost is there.  When did your T2 hit 21psi on your GPZ750 when you pinned the throttle from a stop or slow roll (for a ball park comparison)?

Thank you sir for the pics, give me a great idea of space.

Something to keep in mind, the GPZ was basically a KZ650 head with a larger bottom end. Dual cams, stiffer everything. Even alone the Turbo version made more power without the boost in the top end. Slow as a dog off the bottom though. Which is where most turbo's are unless you are always running in lower gears.

Mine made full boost at about 4500prm. And kept it there all the way up to the redline. Thanks in part to the wastegate/bov and the PC3usb fueling. Even sitting still with no load I could rev the bike a few times and make about half boost. Granted the T2 was a little bit larger than the stock Hitachi H10B (crappy little dryer) but it made some serious numbers in this configuration. I just think the T3 might be too much air volume to spool up right away. Even though there isn't all THAT much difference.

The stock big bore kit from Wiseco made the GPZ 810cc's. I took 900 Ninja stock pitons and cut them down around the tops and crowns to get almost 907cc's. I followed what another owner/racer did and it worked great. But put the bike right on the borderline of being streetable. He fried about 150 pistons before getting the cut shape just right.

Sad part is what I can do to the GZP750's doesn't really apply here to the CB's. I wish it would though.  I don't really mind starting over.

[j squared]

What T2 were you running? ^

[HavocTurbo]

Air Research T2... cannot remember the specs... I'll see if the paperwork is still around.

[Bamboozler]

Havoc - Just reading again all the work that went into you GPZ, with the motor alone, even gets me somewhat annoyed to hear it's life short changed... All I can picture is the bike laid down after the drunk hit it and you on your knees with your raised arms and head facing the sky belting out a horrific scream of noooooooo...   

I'm just going to have to see what I get with the T3 I have, thinking I'll be in the upper end of the ballpark of what I figured.  One bonus is that when motor work comes around the boost response can improve if the displacement is increased.

I'm a happy camper tonight.  The bike was fired up for the first time with its new turbo!!  I was happy to see it caught with a stummble even on the first blip of the starter button, the second try sealed the deal and she was up and running.  The sound.... The CB sounds like it was unjustly killed in its prior life and reincarnated back on earth to seek vengeance... More throaty and full of attitude, I like.   Even with the short dump 2.5" exhaust it's no louder than with 4-1 Kerkers it had prior.  I'll start a project review soon.

[j squared]

Gotta love snail-induced backpressure! The worlds best silencer.

[scartail]

Do they make T2/T3 hybrids? T2 turbine with T3 compressor?
I know they can custom make them. But are they common?

[j squared]

The most notable one is a GT2871R, basically a disco potato exhaust side with a 71mm wheel on the compressor side.  It would be considered a hybrid I guess since the 71mm wheel originally comes from a GT3071.

People also clip (aka clearance) various T2 housings to install bigger compressor wheels from T3-framed CHRA's.  This is really common with turbos from stock applications, like Nissan's RB20/25 turbos and Mitsubishi's 14B/16G.  on that note I would consider a 20G Mitsu turbo to be somewhat of a hybrid, it is larger but available with a T2 flange and a smaller exhaust housing.


I think a great turbo to run on a cycle would be an EvoIII 16G, a Super-16, or a GT2860RS disco potato. All three would give killer spool and are capable of pushing over 300hp on a 2.0L engine.

[1080]

 I looked at the post by Scartail about the Yamaha 650 project.

He figures he needs about 400watts to run his system and he pulled the guts of a Holden alternator and transplant in the bikes stock alternator housing, then he makes his own permanent magnet rotor.

Sounds like one way to solve the cb's power output limits is by transplanting a better alternator system.

I've been told that the Police CB 750s had stronger alternator output.
They ran a police radio, siren and extra lights. The alternate must be good for an extra 10 amps?
But it would be nice to know if the part numbers for the alternator differs.  

Or was it just ran by another extra battery and charged external.

Maybe someone on the forum could confirm the Police bike alternator output.

[754]

to see the alternator construction check page 2,  Post # 35 of this thread...

[bucky katt]

Interesting idea with the vacuum tubes going to the float bowls, Ill bet that makes the seals there critical huh?

Can't take credit for the vac tube idea, all of the turbo carburetor platforms do have some form of manifold reference to their fuel bowls to allow the system to work.  You are correct on the sealing being critical. When I first plumbed up the fuel system and fired up the pump the regulator was set to 20ish psi.. I had a nice little fuel water fall  .  Since then I set the base pressure to 3psi, replaced the O-rings on the fuel tubes that connect the carbs, and am waiting on float bowl gaskets for two bowls that were weeping at ~13 psi.

Bam, you're using stock carbs right?

Yes I'm giving the stock 78 CB750F PD42A's a try to see if they'll work out.  Not as ideal as a constant velocity type carbs, but I thought I'd see if they would work.  During the end stages of the intake fab I came across a thread here that was started by cafebob which detailed his adventure in fitting up a set of 85 CB650SC Nighthawk CV carb for use with his CB750 (http://forums.sohc4.net/index.php?topic=28898.0).  I since then acquired a set of those CB650SC carbs and have them in my back pocket in case there's a deal breaker with the cable slide stockers that I'm currently using.  I would have to replace the intake's runners with larger O.D. tubes to accommodate the larger diameter inlets on the 85 Nighthawk carbs, or fab up an adapter of sorts to make use of them.

I'd appreciate a pic of this system actually on the bike without the tank. Gives me a sense of space in the frame and under the tank.

The included pics are the best I have at the moment, next time I visit the bike I'll snap a pic to get the tank-less top view that you are looking for.  I can say the fuel pump is almost touching the battery box, but you can disconnect the pump and regulator from the intake and set them aside (keeping the fuel lines connected) and remove the intake to get at the carbs for removal.







Enjoying the exchange of info regarding the building of these motors for boost, taking notes.

i really like the extra crankcase vent running off of one of the tappet covers. something i'd never thought of doing. is there some kind of air/oil seperator in the fitting or line?

[mgbgt89]

The most notable one is a GT2871R, basically a disco potato exhaust side with a 71mm wheel on the compressor side.  It would be considered a hybrid I guess since the 71mm wheel originally comes from a GT3071.

People also clip (aka clearance) various T2 housings to install bigger compressor wheels from T3-framed CHRA's.  This is really common with turbos from stock applications, like Nissan's RB20/25 turbos and Mitsubishi's 14B/16G.  on that note I would consider a 20G Mitsu turbo to be somewhat of a hybrid, it is larger but available with a T2 flange and a smaller exhaust housing.


I think a great turbo to run on a cycle would be an EvoIII 16G, a Super-16, or a GT2860RS disco potato. All three would give killer spool and are capable of pushing over 300hp on a 2.0L engine.

How well suited would a 14b be to an 836? I've got one laying around from when i went to a 16g on my DSM. Not sure how it compares in size to a t2.

[j squared]

I have no idea, never tried boosting a bike   As far the turbo goes its small enough to give good spool Im sure, but you cant compare it to a generic T2 since there are dozens of different T2-based turbos out there.

[Bamboozler]

I've been told that the Police CB 750s had stronger alternator output.
They ran a police radio, siren and extra lights. The alternate must be good for an extra 10 amps?
But it would be nice to know if the part numbers for the alternator differs.  

Hmm, this is interesting, going to do some digging on the police models and see what can be found (anyone else know of anything regarding them?)... To find a bolt in higher output generator would be by far the best solution...  Not hearing people do this mod already makes be wonder if these models and their possible generators are rare, or pricey?

i really like the extra crankcase vent running off of one of the tappet covers. something i'd never thought of doing. is there some kind of air/oil seperator in the fitting or line?

Sorry for the delay in getting back to you bucky katt, just got back in the States from a trip.  The hose is a bit misleading, its actually the return line for the turbo's oil drain. Oil draining from the turbo gets drawn into the pump, then pumped through the oil cooler and back to the motor via the modified tappet cover you see.  However you do bring up a good point regarding the crank case ventilation.  I haven't gotten to the point of getting the bike down the road yet (just started the bike before vacation).  With the increased cylinder pressures, if there is a problem with needing to evacuate crank pressure to help the rings seal up I thought about plumbing a pipe into the exhaust that would be connected to a tappet cover in the same fashion or the stock vent bung; this is suppose to create a venturi effect and pull a vaccum on crankcase.  There is a company that sells the tubes, and I can't come up with they're website at the moment (they seem simple to mimic as well). Or popping an additional hole in a tappet cover as you suggested with a catch can may be all that's needed.

How well suited would a 14b be to an 836? I've got one laying around from when i went to a 16g on my DSM. Not sure how it compares in size to a t2.

To help put the 14b into loose perspective.  My Chinese turbo has "DSM EVOIII" printed on the side of the compressor.  Supposedly rated for 320HP.  I would think that if you would throw a generally lesser flowing 14b on a larger cc motor you're going to see a better throttle response and full boost and a lower RPM.  I was offered a free 13b for the project from my buddy who pulled it off a automatic turbo DSM; it was a bit bulky in the turbine to fit easily up front (blame the D#$m filter housing for getting in the way).  Rear mount may not be a problem, never investigated.  I have a 90 Talon TSI AWD with a MHI EVOIII big 16 for my winter car.

[MRieck]

Crankcase pressure will also be an issue with these 1000cc kits. I'm looking into some possibilities

[bucky katt]

i ran a crankcase vent system plumbed into the header collectors on the mustang i had. competition engineering had the check valve fittings that went into the collector so exhaust gasses wouldnt back up into the motor. worked great and actually decreased oil consumption and quarter mile times.

[754]

I will try to check the parts book, I have a 71 with Police Euip for the 750s in it.
 Pretty sure there was no special electrical for it..

[Bamboozler]

Crankcase pressure will also be an issue with these 1000cc kits. I'm looking into some possibilities

Interested to see what you come up with.  The adding of the venturi style system will not be an option for most without a custom exhaust that you can hack into without concern.  If you have stock or aftermarket non turbo exhaust, cutting into them is not a option that is even going to be debated by most. 

i ran a crankcase vent system plumbed into the header collectors on the mustang i had. competition engineering had the check valve fittings that went into the collector so exhaust gasses wouldnt back up into the motor. worked great and actually decreased oil consumption and quarter mile times.

You are spot on regarding the application of that venturi system; thanks for the check valve reference too.  I have a buddy that did the same this summer for his turbo 4 cylinder application with favorable results from what I last heard.  Good to see that you have a first hand account of the system's success.

I will try to check the parts book, I have a 71 with Police Euip for the 750s in it.
 Pretty sure there was no special electrical for it..

Would be sweet if there happens to be, but if not and least it will be confirmed.

[754]

Checked parts book for 69 - 71 750,, all the parts in the dyno cover are the same those years..

 We need someone to check a 76 or 78 partsbook, see if any choices show up in there.

[ajracer]

since you guys are on the topic of forced induction, I thought I might run my idea by you. I have been thinking of building a blown 550 or 750 using the compressor side of a small turbo driven off the starter port. The starter clutch would be welded up and I would hallow the starter and attach a pulley to drive it. I think it would spin up pretty fast but I don't know if it would be fast enough to get real pressure. Has anyone ever seen a turbo housing used as a supercharger?

[scartail]

A centrifugal supercharger would be what you would be making. Check out procharger.

You have to have gearing to get the compressor to do work. A turbo could spin up to 100K rpm! Gota do the math.


Btw, the shaft in a turbo is connected (welded? pressed fitted, with a super tight fit?) to the turbine blades, not the compressor. So trying to use the compressor side, you would need a custome shaft.

[754]

A buddy has used Rotrex, very similar to Prochargers, as well as the latter... they turn around 100K, geared up drastically
 He says they are way higher effeciency than a Roots Type

 He is thinking of trying a Fageol Roots type (for looks) on another build.. none of his apps were 4 cylindrr BTW..

 Fageol start at around 1500 bux
 Rotrex around 2500

 Procharger.. usually only sold in complete kit

[JLeather]

Man, you guys are making me wanna get off my butt and get back to work on my turbo motor too.  I'm going with the vintage draw-thru style myself.  Yeah, I know the drawbacks, but I've got the whole ATP kit already and I'm not looking to squeeze every hp outta this bike, just a really fun cruiser.  Scraping up the dough for custom pistons right now, and then I'm ready to stick it all together.

[Bamboozler]

Scraping up the dough for custom pistons right now

That got me thinking about turbo territory compression ratio pistons for the CB750s.  Where might you find any piston sets in the 7.5-8.x CR range?  I hit up a few CB web sites and could find nothing in that CR; all in the 10+.  I'm thinking that's why you are springing for custom pistons? What's the details on them slugs?

Would be nice to work a larger displacement into the picture as well; big bore with lower compression?  Or would you have to play tricks with the big bore kits out now by using thicker head gaskets, or mix and match specific year cylinders and heads?

[JLeather]

I went through tons and tons of conversations with engine builders, racers, former turbo guys, etc trying to figure out the best way to get the compression down.  Here are some of my earlier options and why I didn't.

Stock pistons ceramic coated.  Swaintech has a very nice heat-resistant coating for $38/piston.  This would take care of the heat side of things, but a cast piston just won't take much boost for long and I didn't wanna always be worried about it so this was scrapped.

Wiseco K836 forged kit with base gasket spacer.  This was my next plan.  I forget off the top of my head exactly how much I needed to raise the cylinders but I seem to recall dropping a full point every .035" or so.  Wiseco's are 10.25:1, and with some chamber work I could get that to maybe 10:1 SCR, meaning I'd need atleast .060" of base gasket space to get back to turbo-friendly ranges.  At that kind of spacing the stock cam chain won't reach anymore.  Allegedly, according to a guy who used to put DOHC900 rods into his engines (1.5mm longer) and space them up you can make a timing chain fro #219 shifter-kart chain.  This may have been a possibility still, but in the end the big valve pockets and overly large squish would have cost hp and made for a kludgy setup.  Just not in the cards.

I also considered DOHC750 rods (1.5mm shorter) with Wisecos.  Not convinced they're strong enough, and I'd have the same squish problems as above so this got scrapped as well.

Last possibility was F-head on a Wiseco kit.  This would only get me down to somewhere around 9.5:1.  Better, but not great for a turbo.  Also, the overly large exhaust ports would make the turbo very sluggish.  Add in the f-head reliability problems and cost to rebuild and I scrapped this idea as well.

I happened across a set of MTC forged 836 8:1 pistons earlier this year and got my hopes up, but when I sent them to Mike Rieck to be checked over and refurb’d they were found to be no good.  30 year old parts and all, I wasn’t all that surprised.

This brings me up to the present.  I noticed that Dynoman listed stroker pistons with the pin moved.  I figured a stroker piston might also work in a turbo so I eMailed him.  He said they can get custom J&E pistons made in pretty much any compression ratio I wanted.  So we settled on a set of forged 836 pistons in about 8:1.  They’re gonna run the same rings as the Wiseco K836 kit because they’re easy to get, inexpensive, and good quality.  APE tool steel wristpins finish it off.

At the moment I’m debating O-ringing the block.  I’m not gonna be running all that much boost, but I probably oughta just do it and prevent trouble down the road.

Next on my to-do list is figure out the clutch basket/clutch pack necessary for this bike.

[Bamboozler]

Thanks for the detailed reply JL, I appreciate the brain dump on the matter. I like your solution, bigger displacement and and a good CR for boost.  When the time comes I'd be perfectly happy follow that path too. I'm assuming they could do the same for their 77-78F flavor pistons as well; hope so.

Do post what you find out regarding the clutch solution as well. The only thought on the matter I gave was to get heavier springs, but I'm not sure how far that will go.  I saw someone makes a lock up which would be on the bullet proof side of the spectrum, but was a bit spendy for clutch solution; as expected. 

Any upgrades in the rod and cam dept. going into your motor?  How much boost are you looking at once everything is said and done?

(Edit to add: I see your clutch thread, ignore posting on this matter)